Means for operating mercury switches



2- M. A. E. LEBLANC 1,844,402

MEANS FOR OPERATING MERCURY SWITCHES Filed June 13. 1927 INVENTOR BY v IATTORNEY Patented Feb. 9, 1932 warren i MAURICE aoo'os'rn EUGENE TLTELAC, 01? SUEESNE$, ZRATLQ'QE, AESIGNOR, BY IKESNE ASSIGNMENTS, T ELMLEEICVAPQR. COMPIiNY, -01 HOBOKEN, NEW JERSEY, A CORPORATIGN (03F ItlE'tiVJERSEY MEANS F03 QL ERATING MERCURY Application filed June 33, 1927,Serial No. 198,612, and in France June 23, 1928.

- ture in which'causes bending, this latter phenomenon being employed toproduce tilting of the switch, thus causing therein movements of themercury necessary for its operation.

Electric switches with mercury contacts in a neutral gas have nothitherto received all the applications in electrical apparatus whichtheir great simplicity and great surcness of operation merit. This isdue to the fact that this latter requires slow displacements of fairlylarge amplitude which it is not always easy to realize with the ordinaryelectromagnetic relays.

The same thing may be said of compound strips or thermoelectric elementsby which is meant an aggregate of two metallic strips soldered togetherover the whole extent of one surface of each of them, the metalsconstituting the two strips being selected with coefficients ofexpansion as different aspossible.

Under these conditions any change of temperature in the bi-metallicstrip is shown by a change of curvature. This change of shape hasalready been used to close or to open electric contacts, but theweakness of the mechanical forces, which come into play generallynecessitates somewhat considerable complications to ensure perfectoperation.

The construction of mercury switches employed in carrying the inventioninto practice may be any whatever.

Fig. 1 shows an arrangement in which there is a rigid attachment betweena iii-metallic strip K and a mercury switch L. The bimetallic strip K,which is located vertically when at rest and rigidly fixed at its upperend M, carries at its lower end a horizontal bar 0 to which are attachedthe grips holding said switch L. The terminals of the latter as well ashe free end of the bi-inetallic strip are connected by flexible leads tofixed terminals N. While there has been shown as an example the case ofa reversing switch hang from a bimetallic strip heated by its ownresistance, it is to he understood that with this arrangement there maybe employed any type of mercury switch and that any of the usual meansof heating the bi-metallic strip may be employed.

The sensitiveness of the device may be increased by compensating for theweight of the mercury switch by immersing it in a liquid having adensity approximating its mean density as Sll0, 'n in Fig. 2; thisarrangement has the advantage of damping the oscillations caused byexternal vibrations.

Claims: 1. In combination, a mercury switch and a liquid bathsurrounding said switch, said bath having a density substantially equalto the average density of said switch.

2. in combination, a mercury switch, a thermo-sensitive elementsupporting said switch, and a liquid bath surrounding said switch havinga density substantially equal to the density of the switch.

In testimony whereof I afiix my signature.

PJAURHCE AUGUSTE EUGENE LEBLANC.

